We've done some testing and found that in Windows 7, the F9 key was able to still work but the F7 key didn't. In Windows 10, neither keys seem to work. We're not sure exactly if updated version of powershell has deprecated these shortcuts.

sorry about the delay in research time. I've traced a couple of items down for this F7 and F9. The PSReadLine is embedded. But...as always, there is a but it's not as functional as it once was the new recommendation instead is CTRL+R (Reverse History) and CTRL+S for an interactive search.

You can run Get-PSReadlineKeyHandler to list the available shortcuts and Set-PSReadlineKeyHandler to assign F7 to the search history functions